A. Field of the Invention
The present invention relates to a thermostatic gas valve including a locking element for locking the valve in the off position and for defining first and second positions of the valve for adjusting the flame height and temperature, respectively, of a gas burner.
B. Description of the Prior Art
Modern gas stoves often include at least one burner that may be controlled as to temperature and height of the flame. In this manner, the operator of the burner may ensure proper cooking of foods.
The valve employed to control the burner typically includes a thermostatically actuable valve that senses the temperature of a pan or similar article placed upon the burner and controls the flame to maintain the temperature selected. The gas valve also includes a rotary valve disc that may be rotated to control the maximum height attained by the flame when the thermostatically controlled valve is fully opened.
Both the thermostatic valve and the rotary disc are actuated by a valve shaft and stem mounted within the housing of the gas valve. The sleeve may be axially moved within the housing from an off position to a first position whereupon the sleeve and stem may be rotated to actuate the rotary disc to select the desired flame height. Thereafter, the shaft and stem may again be axially moved to a second position whereupon the shaft and stem may be rotated to actuate the thermostatic valve thereby selecting the desired temperature.
An example of a typical prior art valve of this type is disclosed in U.S. Pat. No. 3,030,025 assigned to the assignee of the present invention and incorporated by reference herein.
In recent years regulating authorities governing the manufacturing of thermostatic gas valves have been considering, and in some cases implementing, regulations requiring the valve to be locked in the off position. In addition, it has been considered desirable from a marketing standpoint to include definite positions of the thermostatic valve such that the shaft and stem of the valve may be axially moved from the off position to a first position and must then be rotated to the selected flame height before the shaft and stem may be axially moved to a second position. This provides the operator with definite positions acknowledging the operations that must be performed. It would be desirable to meet these requirements without substantial modification of the existing structure of thermostatic gas valves.